PREPARATION OF SM2FE17NX ANISOTROPIC POWD ER BY MECHANICAL GRINDING IN NH3 ATMOSPHERE

Sm2Fe17Nx, powders with magnetic anisotropy have been prepared by mech anical grinding (MG) in NH3 atmosphere using a rotary ball mill. The h ydrogen content of Sm2Fe17Nx powders after MG increased rapidly till 7 2 Its with increasing MG time, and showed the maximum at 72 ks. Beyond 72 ks, it decreased with increasing MG time. On the other hand, the n itrogen content monotonously increased with MG time, and it was kept c onstant beyond 432 ks. Though the powder after MG for 288 ks absorbed 35000 ppm of nitrogen, the magnetic properties of this powder were det eriorated due to the distortion which was introduced into the powder d uring MG. The powders were prepared by MG for shorter periods between 18 similar to 144 ks and subsequent nitriding. Their magnetic properti es such as remanence and rectangularity of the demagnetization curve w ere extremely improved. The remanence over 1.0 Wb.m(-2) and the maximu m energy product of 129 kJ.m(-3) (16.1 MGOe) were obtained for the pow ders prepared by MG for 18 and 36 ks and subsequent nitriding. X-ray d iffraction patterns of the powders aligned in the magnetic field showe d the growth of the (006) peak. This indicates that these powders have the magnetic anisotropy. It is considered that an increase of MG time deteriorates the magnetic anisotropy due to the pulverization of powd ers.